Final answer:
In the sentence provided, 'appreciate' is the simple predicate, indicating the action taken by 'clients,' the subject.
Step-by-step explanation:
In the sentence "Clients appreciate the attention to detail," the simple predicate is appreciate. In English grammar, the predicate is the part of a sentence that tells us what the subject does or is. The simple predicate is the main verb in the clause that refers to what the subject is doing. In this case, "clients" is the subject, and what they are doing is expressing gratitude or recognition for the "attention to detail." Hence, "appreciate" is the simple predicate because it represents the action being done by the subject.